Semiautomatic firearms fire one round every time the trigger of the weapon is pulled. Such a weapon utilizes a portion of the energy of a firing cartridge or shell to extract the fired cartridge case or spent shell and chamber the next round. Several states have passed legislation regulating certain features of semi-automatic firearms. Currently possessed semi-automatic firearms that have more than the allotted number of regulated features usually must be altered, registered, or surrendered to law enforcement officials. As a result, firearm users living in or travelling to these states are often unsure about the legality of the firearms they possess.
Various attempts have been made to comply with firearms laws by altering the regulated features of these weapons. Such attempts generally involve removing or modifying one or more of the regulated features to bring particular firearms into compliance with the laws.